Hydraulic drive system

ABSTRACT

A hydraulic drive wherein a plurality of hydraulically actuated pistons move a ring gear through an orbital path thereby imparting rotation to an inner gear with which the ring gear meshes. The ring gear is supported for movement by a parallelogram linkage. Valve means driven by the ring gear control the operation of the pistons. The drive system generates a high level of torque even at low speeds and with high volumetric efficiency.

United States Patent 72] Inventors Spencer Bowman 1635 Riverside Drive, Lakewood, Ohio 44107;

Anthony Nevulis, Wickliffe, Ohio 815,251

Mar. 17, 1969 June 29, 1971 [21 Appl. No 22] Filed [45] Patented [73 Assignee said Bowman, by said Nevulis [54] HYDRAULIC DRIVE SYSTEM 9 Claims, 7 Drawing Figs.

[52] U.S.Cl 91/481, 91/495,91/180,9l/182 [51] 1nt.Cl F0lb1/06, FOlb 13/06, F011 33/02 [50] Field of Search 91/182, 188, 203, 56,77, 78,180, 481, 494, 495

[56] References Cited UNITED STATES PATENTS 666,553 1/1901 Petee etal. 91/182 834,033 10/1906 Tuttle 91/56 1,528,836 3/1925 McElvaney..... 91/182 533,317 1/1896 Richards 74/803 1,260,243 3/1918 Moore 74/804 1,865,493 7/1932 Whitfield 123/81 1,874,336 8/1932 Niven 123/55 1,921,092 8/1933 Newton 137/625.27 2,011,820 8/1935 Meyer 123/81 2,069,007 1/1937 Fontana 74/393 2,105,846 1/1938 Ruliancich 74/665 2,382,482 8/1945 Henry 74/764 2,760,439 8/1956 Crookston 123/32 3,052,138 9/1962 Louton, Jr. et al... 74/805 3,058,429 10/1962 Rocheville 91/495 3,272,080 9/1966 Avery 91/186 3,320,828 5/1967 Grant 74/675 3,431,863 3/1969 Waldorf 418/61 FOREIGN PATENTS 13,614 11/1885 GreatBritain 91/56 Primary Examiner-Paul E. Maslousky AttorneyMeyer, Tilberry and Body ABSTRACT: A hydraulic drive wherein a plurality of hydraulically actuated pistons move a ring gear through an orbital path thereby imparting rotation to an inner gear with which the ring gear meshes. The ring gear is supported for movement by a parallelogram linkage. Valve means driven by the ring gear control the operation of the pistons. The drive system generates a high level of torque even at low speeds and with high volumetric efficiency.

pmminwmlsn 3,589,243

SHEET 1 [)F 5 86 e7 8588 4A SPENCER 'cQWiJ/IM By ANTHONY NEVULIS ATTORNEYS.

PATENTEDJUN29|9ZI 3,589,243

sum 3 OF 5 INVIZN'IURS. FENCE BOWMA BY NTHO NEVULI ATTORNEYS.

PmEmfinmzemn 3,589,243

SHEET U 0F 5 INVENTORS, SPENCER BOWMAN ANTHONY NEVULIS ATTORNEYS.

HYDRAULIC DRIVE SYSTEM This invention relates to the field of hydraulic motors and, more particularly, to a hydraulic motor capable of generating a high level of torque at low speeds with high volumetric efficiency.

The invention is particularly applicable to apparatus such as a winch in which there is a high torque requirement at the start of its operating cycle and the invention will be described with particular reference to this type of apparatus although it will be appreciated that the invention has broader application and may be used whenever a hydraulic motor is found to be ad vantageous.

Hydraulic motors of various constructions are well known; however, the hydraulic motors which have been developed up to this time have an extremely poor volumetric efficiency in the lower speed ranges. For example, a typical prior art hydraulic motor operated at a speed of l revolution per minute might well have a volumetric efficiency as low as percent. It is normally necessary to operate the prior art hydraulic motors at speeds in the range of 300 rpm. before the volumetric efflciency begins to reach an acceptable value. It is not until these motors are operated at the speeds of 2000-3000 r.p.m. that the volumetric efficiency begins to look rather good.

With this shortcoming in the prior art motors, it is a generally accepted fact that hydraulic motors are not satisfactory for low speed operation. Obviously, the result is that the market for this type of motor is somewhat limited.

Another problem which has been encountered in low speed drives is the requirement, in some applications, of a high torque at the start of the drive cycle. A winch is a typical example in which the drive system must be capable of delivering a sufficiently high level of torque at low speeds at the very start of the operating cycle of the winch. In such circumstances it is not satisfactory to have the drive system come up to speed before applying the load. The prior art has approached this problem by employing a high-speed high-torque drive together with a gear reducer which, in combination, provided the necessary low-speed high-torque output. However, the usual gear reducers employed, depending on the amount of gear reduction, tend to be rather large units and are relatively expensive. Moreover, it is necessary to employ with this type of drive system a separate braking or locking device.

The present invention contemplates a new and improved hydraulic motor which overcomes all the above referred to problems, as well as others, and which provides a low speed drive having a high volumetric efficiency and capable of generating a high output torque at the start ofits operating cy cle. In addition, the present invention is relatively simple in construction and economical to manufacture and has a broad range of potential applications.

In accordance with the present invention, there is provided a hydraulic motor comprising a housing, an output shaft rotatably supported in the housing and first inner gear means operatively connected to the shaft for rotation therewith. A second ring gear means is disposed in the housing with the inner gear means having external teeth and the ring gear meanshaving internal teeth. The ring gear means is supported for orbital movement into and out of meshing engagement with the inner gear means. The orbital movement of the ring gear means is achieved by a hydraulic motor. The number of teeth on one of the gear means is less than the number of teeth on the other of the gear means thereby effecting a gear reduction. In addition, the hydraulic motor drive is so designed that leakage may be readily controlled thereby obtaining a high volumetric efficiency. Moreover, the hydraulic drive system provides a hydraulic lock which, in combination with the meshing gears, provide a self-locking feature.

In accordance with one specific aspect of the invention, there is provided a novel support arrangement for the ring gear, which support is, in effect, a parallelogram or pantograph whereby the ring gear may move to positions of eccentricity relative to the longitudinal axis of the inner gear.

In accordance with another aspect of the invention, the operation of the hydraulic motor is controlled by valve means which, in turn, are driven by the ring gear.

One of the principal objects of the invention is to provide a hydraulic motor which is capable of producing high torque at low speeds with a high volumetric efficiency.

It is another object of the invention to provide a hydraulic motor which is relatively simple in construction and which may be economically produced for a wide variety of applicatrons.

Still a further object of the invention is to provide a drive system which is capable of delivering high torque at low speeds at the start of its operating cycle.

The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail hereinafter and illustrated in the accompanying drawings which form a part hereof.

Referring now to the drawings wherein like reference numerals indicate like parts in the various views:

FIG. 1 is an end elevation view ofa hydraulic device incorporating the principles of this invention, as applied to a winch; FIG. 2 is a sectional view along line 2-2 of FIG. 1;

FIG. 3 is an elevation view, partially in section, illustrating the support for the meshing gears;

FIG. 4 is a sectional view taken along line 44 of FIG. 1,

FIG. 4A is a sectional view of one of the valve housings,

FIG. 5 is a side elevation view partially in section of a modified form of the invention,

FIG. 6 is a sectional view along line 6-6 of FIG. 5.

Referring now to the embodiment of FIGS. 1 to 4, the invention will be described with particular reference to a drive for a winch. Although winches typify the type of environment in which the present invention may find particular utility, it is to be understood that the invention has far broader application.

As shown in FIG. 2, a winch assembly, indicated generally by the reference numeral 10, includes a cylindrical drum 12 with spaced apart radially extending flanges 14. The drum 12 is rotatably supported by bearings 16 for rotation relative to a fixed or stationary housing, indicated generally by the reference numeral 20.

For purposes of this disclosure, the housing may be considered to be in two parts, a first part 21 which is the winch housing and a second part 22 which comprises the housing for the winch drive unit. As is apparent, the two portions 21, 22 of the housing may be integral and supported on a common base 23.

The winch portion of the housing includes a first end wall 24 and a second end wall 25 with the end wall 25 being common to the drive portion 22 of the housing 20. A shaft 26 is rotatably supported by a bearing 27 in the end wall 24 and by a bearing 28 in the end wall 25. As is apparent from FIG. 2, the shaft 26 extends through the cylindrical winch drum l2 and includes portions 29 on which the bearings 16 are supported.

To interconnect the winch drum 12 with the shaft 26, there is provided a hydraulically actuated friction blutch assembly, indicated by the reference numeral 30. This clutch assembly includes a piston member 32 which is slidably received over the shaft 26 with the piston member including a rearwardly extending cylindrical tail portion 33 which cooperates with the portion 29 of the housing 21 to define therebetween a fluid chamber 34. A plurality offriction plates 36, 38 are positioned between the cylindrical drum l2 and the shaft 26. The friction plates 36 include external teeth adapted to cooperate with the drum 12 while the friction plates 38 have internal teeth cooperating with the shaft 26. It will be appreciated that as the friction plates 36, 38 are brought into frictional engagement, drive will be transmitted through the friction plates from the shaft 26 to the drum I2.

To clamp the friction plates 36, 38 between the forward end 39 of the piston 32 and a backing member 40, there is provided a source of fluid pressure which may be selectively introduced into the fluid chamber 34 through fluid passages 41,

42 in the shaft 26. It will be appreciated that as the fluid pressure is introduced to the fluid chamber 34, the piston 32 will move to the left as viewed in FIG. 2 thereby clamping the friction plates 36, 38 into frictional engagement and causing transmission of the rotational motion from the shaft 26 to the winch drum 12.

The drive unit for the shaft 26 will now be discussed. This drive unit, indicated generally by the reference numeral 50, is carried within the drive portion 22 of the housing 20. The drive unit includes an externally toothed inner gear 52 which is secured for rotation by splines 53 or similar means to one end of the shaft 26. An internally toothed outer or ring gear 54 is received over the inner gear 52. The inner diameter of the outer gear 54 is substantially larger than the outer diameter of the inner gear 52 and gear 54 has a greater number of teeth than gear 52, for a purpose hereinafter discussed.

Referring now to FIG. 3, the support for the outer or ring gear 54 is illustrated. This support comprises a pair of links 56 which are pivotally connected at 57 to the housing 20. The other end of each link 56 is pivotally connected at 58 to a support ring 59. In this manner, the ring 59 is supported for swinging movement transverse to the longitudinal axis of shaft 26.

The support ring 59in turn pivotally supports at 61 one end of each of a pair of links 60. The other end of each of the links 60 is connected by a pivot pin 62 to the ring gear 54 so that the gear 54 may swing through a path that is transverse to the path of movement ofring 59.

As is apparent from FIG. 3, the pivot pins 62 are spaced 180 around the periphery of the ring gear 54. Similarly the pivot pins 58 for the two links 56 are spaced by 180 around the support ring 59 with each link 56 being circumferentially spaced by 90 from one of the links 60. The combination of the links 56 and 60, together with the supporting ring, in effect, comprises a pantograph or parallelogram support for the ring gear 54. As a result of the combined pivoting movements, of the links 56, 60, each point on the ring gear 54 moves through a path which is elliptical or orbital in shape. It will be appreciated that as the ring gear 54 traverses this orbital path, a portion of the teeth on the ring gear will mesh with the teeth on the inner gear 52, while the remaining portion of the ring gear teeth will be spaced from the inner gear, as shown in FIG. 3. The intermeshing ofa portion ofthe ring gear teeth with the inner gear will continue progressively around the entire circumference of the inner gear 52 as the ring gear traverses its I orbital path with the meshed teeth transmitting motion from the ring gear to the inner gear.

The ring gear 54 is driven through its orbital path by a plurality of hydraulically actuated pistons 64. In the embodiment shown, eight pistons are employed, only one of which is illus trated. However, it will be appreciated that the number of such pistons may be varied depending upon the particular plication of the drive unit.

A connecting rod 65 is pivotally connected at its inner end to the ring gear 54 and at its outer end by a pin 66 to the piston 64. The piston 64 is slidably received in a cylinder 68 carried by the cylindrical sidewall 69 of the housing 20. It will be appreciated that as the piston 64 reciprocates in cylinder 68, the longitudinal sliding movement of the piston 64 is translated into the desired orbital movement of ring gear 54 through the pivotal connections oflinks 56, 60.

The actuation of the pistons 64 in cylinders 68, which in effect constitute hydraulic motors, is effected by the selective introduction of hydraulic pressures into each cylinder chamber through a manifold valve and porting arrangement now to be described. Thus, there is provided a manifold ring 70 which is secured to the side wall 69 of housing 20. This manifold'ring includes a pair of annular grooves constituting an inlet or high pressure passage 72 and an outlet or low pressure passage 74. The passage 72 is connected by suitable means to a source ofhigh pressure fluid while the passage 74 is connected back to sump or tank.

Associated with each piston 64 and cylinder 68 is a valve mechanism, indicated generally by the reference numeral 76.

This valve mechanism comprises a valve housing 78 having a valve chamber 80 in which a valving element 82 is slidably received. This valving element comprises a spool valve having cylindrical end portions 83,84 interconnected by a reduced diameter portion 85. Three annular grooves are spaced along the cylindrical bore or valve chamber 80 with the first groove 86 being associated with the end 83, the second groove 87 being concentric to the reduced diameter portion and the third groove 88 being associated with the end 84. The groove 86 is connected by a fluid passage 89 to the annular high pressure passage 72 while the groove 88 is connected by fluid passage 90 with the low pressure annular passage 74. The groove 87 is connected by fluid passage 91 with the interior 92 ofthe hydraulic cylinder 68.

It will be appreciated that with the spool valve 82 shifted to the left, as viewed in FIG. 4A, the high pressure in the passage 72 will be communicated through passage 89 and grooves 86, 87 to the passage 91 where it will be introduced to the fluid chamber in cylinder 68. In this condition of the valve, the low pressure port 90 will be closed by the end 84 to the valve 82. By shifting the valve 82 to the right, as viewed in FIG. 4A, the high pressure passage will be closed and the cylinder 68 will be placed in communication through passage 91, groove 88 and passage 90 with low pressure passage 74.

The movement ofthe spool valve 82 is controlled and coordinated by a cam plate, indicated generally by the reference numeral 95. This cam plate is secured by appropriate means to the ring gear 54 and, hence, has an orbital movement which corresponds to that of the ring gear. As perhaps best viewed in FIG. 1, the periphery ofcam plate 95 has a plurality of rectangular cutout portions 96 which are defined by opposed arms 97. The arms 97 are spaced apart a distance equal to the length of the spool valve 82 with the facing surfaces 98 of the arms being adapted to slidably engage the outer extremities of the spool valve 82. As is readily apparent from FIG. 1, the orbital movement ol'cam plate 95 causes the cam plate to move, in sequence, radially toward and away from each of the valve housings 78, which radial movement is accommodated by the slotted or cutout portions 96. In addition, the orbital movement also the plate to move a limited amount circuml'erentially, thereby causing the arms 97 to impart'longitudinal reciprocation to the spool valves 82.

The foregoing described mechanism operates in the following manner to transmit drive to winch 12. Assuming the parts to be in the condition illustrated in FIGS. 1 and 2 it is apparent that the piston in the 12 oclock position is at bottom dead center while the piston at the 6 oclock position is at top dead center and the spool valves 82 associated with each ofthe two pistons are centered in their valve housings with both the inlet and outlet ports blocked. The other valves and pistons are in various intermediate positions. For example, the spool valve 82 at the 9 o'clock position is fully shifted to the left whereby the interior of cylinder 68 is in communication with the high pressure 72, while the opposed valve 82 at the 3 oclock position is fully shifted to the right whereby the interior of that cylinder is in communication'with the low pressure passage 74. It will be appreciated that the pistons exposed to the high pressure are caused to reciprocate which, in turn, causes ring gear 54 to shift on its pivoted linkage supports carrying with it the cam plate 95. As the cam plate shifts, the arms 97 associated therewith cause the spool valves 82 also to shift. For example, the shifting of the ring gear 54 and the cam plate 95 causes the cam plate to move up and in a clockwise direction as viewed in FIG. 1, thereby shifting the spool valve 82 at the l2 oclock position to the right and the spool valve 82 at the 6 o'clock position to the left. The shifting of the valve 82 in the l2 oclock position causes the piston chamber to be placed in communication with the low pressure port whereby the piston 64 may move upward from its bottom dead center position. Conversely, the shifting of the valve 82 at the 6 o'clock position causes the piston 64 to be placed in communication with the high pressure fluid whereby it is forced to move from its top dead center position. It will be appreciated that similar actions occur at each of the valve and piston assemblies so that various ones of the valves are in various stages of opening and closing at any given point in the cycle and the pistons are likewise in various stages of moving toward or away from the top and bottom dead center positions.

As the pistons reciprocate, the ring gear 54 is moved through its orbital path whereby the teeth of the ring gear progressively engage and disengage the teeth of the inner gear 52. As the teeth of the ring gear 54 are moved into engagement with the teeth on gear 52, the wedging effect which results from the meshing of the inclined surfaces on the teeth imparts a rotative movement to gear 52. This rotative move ment is supplemented by the limited arcuate movement of gear 54, all of which combines to rotate both gear 52 and shaft 26.

With hydraulic pressure introduced to the fluid chamber 34, the piston 32 is actuated to clamp the friction discs 36, 38 whereby the rotary movement of the shaft 26 is transmitted to the winch drum 12.

As noted previously, it is contemplated that there will be a differential in the number of teeth between the ring gear 54 and the inner gear 52 thereby to obtain a gear reduction, Although the tooth differential may vary, one specific example is to employ 60 teeth on the ring gear and 54 teeth on gear 52, thereby giving a tooth differential of 6. With the ring gear having 60 teeth, it is apparent that the ring gear must oscillate through its orbital path nine times or 54/6 to produce 1 revolution of the inner gear. Moreover, since each piston completes 1 cycle for each orbital oscillation of the ring gear, it is apparent that each piston cycle nine times for each output revolution of the shaft. Thus, the hydraulic motor operates at relatively high speeds while the winch is driven at relatively low speeds.

In addition, it should be noted that a high volumetric efficiency is obtainable with the above-described drive. The only areas of possible hydraulic leakage in the drive unit are in the piston and cylinder assembly and the valve assembly. Since in each of those instances only pure reciprocating movement is involved, relatively simple sealing problems are presented. Thus, conventional sealing rings may be employed with the piston and it is not at all difficult to control by conventional means any possible leakage around the spool valve. As a result, it is possible to achieve a high volumetric efficiency for this unit. Moreover, because of the absence of any significant leakage in the system, the system is hydraulically locked at any point in its cycle should there be a power failure.

Referring now to the embodiment of FIGS. 5 and 6, a modified form of the invention is illustrated. The winch construction illustrated in FIG. 5 is the same as that illustrated in the embodiment of FIGS. 1 to 4 and, hence, a description of that portion of the embodiment will be omitted. The modifications reside in the support for the meshing gears and the valve and piston arrangement to actuate the meshing of the gears. Thus, one end of the shaft 100 has a radial extension 101 to which is secured, by fastening means 102, an inner gear 103 having external teeth. An outer or ring gear 105 is received over the inner gear 103 and, as in the embodiment of FIG. 1, the ring gear 105 has internal teeth adapted to mesh with the teeth on the inner gear. Also as in the embodiment of FIG. 1, the outer gear 105 is supported by links 106 on a support ring 108. In turn, the support ring 108 is supported by links 110 on the housing so that the ring gear 105 may describe an orbital path in the same manner as that described in connection with the embodiment of FIG. 1. A stub shaft 112 is rotatably supported in one end wall 114 of the housing 116 with the gear 103 being received over and secured to the shaft 112.

A plurality of hydraulic pistons 118 are received in circumferentially spaced hydraulic cylinders 120 formed in the gear 103. As shown in FIG. 5, each piston 118 includes a spring 122 normally biasing the piston radially outward. A roller 124 is secured on the outer extremity of each piston with the rollers 124 being adapted to be received in a roller groove 126 formed on the inner periphery ofthe ring gear 105.

To actuate each of the pistons 118, a plurality of fluid inlet passages or ports 130 are formed in the gear 103 and are in communication with the interior of each of the cylinders 120. A valve plate 132 is rotatably received within a bearing 134 carried by the outer ring gear assembly 105. The valve plate 132 is eccentric in configuration, as is apparent from FIG. 6, and includes a pair of arcuate grooves or passages 136, 138. The grooves 136,138 are concentric to the stub shaft 112 and are adapted to rotate into and out of communication with the inlet ports or passages 130.

A manifold ring is received over the external end of the stub shaft 112 and rotates with the shaft. This manifold ring includes a high pressure passage or groove 142 and low pressure passage or groove 14147 A fluid passage: 146 in the stub shaft is in communication with the high pressure groove 142 while a second fluid passage 148 is in communication with the low pressure groove 144.

Rotation of valve plate 132 is achieved by the orbital move ment of ring gear 105, much in the manner of a crankshaft, with the valve plate rotating through 1 revolution for each orbital cycle of the ring gear. On the other hand, the inner gear 103 and shaft 112 with their associated passages are rotated at a reduced speed which corresponds to the particular speed reduction of the unit.

From the foregoing description it will be appreciated that as the valve plate 132 rotates, the grooves 136, 138 come into and out of communication with each of the passages 130 leading to the piston cylinders 120. The net result is the same as that achieved by the embodiment of FIG. 1. Thus, the reciprocating motion of the pistons 118 caused by the sequential introduction and evacuation of hydraulic pressure to the pistons results in orbital movement of the ring gear 105 into and out of meshing engagement with the teeth on the inner gear 103. As the ring gear 105 moves through its orbital path, rotation is thereby imparted to the ring gear 103, shaft 100 and, by engagement of the friction clutch, to the winch drum,

It will be appreciated that the volumetric efficiency of this latter embodiment will also be very good since, as in the embodiment of FIG. 1, only simple rotary and reciprocating motions are involved. Thus, leakage can be easily controlled so that at any point in the cycle, the unit is hydraulically locked should the power source fail.

With either the embodiment of FIG. 1 or 5, substantial advantages are achieved over the prior art. For example, it is possible with either unit to drive a device such as a winch at speeds as low as l r.p.m. and even lower with very low leakage and high efficiency. Moreover, such speeds can be attained even while delivering torque on the order of 25,000 to 40,000 in-lb.. Still further, this output torque is available from the very start of the operating cycle, thus making the invention particularly attractive for applications such as a winch drive in which high start-up torque is a prerequisite. This latter advantage derives from the fact that irrespective of the point in the operating cycle at which the motor is started, the full hydraulic pressure introduced to the cylinders is directly translated by the pistons to the orbiting ring gear without regard to any crank angle effect.

We claim:

1. In the combination ofa drive mechanism comprising:

a housing,

an output shaft rotatably supported in said housing,

inner and outer gear means in said housing,

said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means,

the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means,

linkage means pivotally connected to said ring gear and said housing and supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, and

means for driving said ring gear through its orbital path whereby said inner gear means and thereby said shaft is rotated, the improvement comprising:

said linkage means comprising a parallelogram support for said ring gear. in the combination ofa drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, linkage means pivotally connected to said ring gear and said housing and supporting ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, and means for driving said ring gear through its orbital path whereby said inner gear means and thereby said shaft is rotated, the improvement comprising:

said linkage means comprising a support ring and supporting links interconnecting said ring, ring gear and housing. 3. in the combination ofa drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring gear through its orbital path whereby said inner gear means and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear, the improvement comprising:

said piston being received in radially outwardly opening cylinders formed in said inner gear means. 4. In the combination ofa drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring gear through its orbital path whereby said inner gear and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear,

valve means for controlling the flow of fluid into and out of said cylinders for said pistons, and means coordinating the operation of said valve means with the movement of said ring gear, the improvement comprising: said valve means comprising a valve plate having fluid passages therein, said piston means including fluid passages in communication with the interior of said cylinders, said valve plate being supported for movement relative to said piston means whereby the passages in said valve plate are sequentially moved into and out of communication with the passages associated with said piston means. 5. in the combination ofa drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring gear through its orbital path whereby said inner gear and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear, valve means for controlling the flow of fluid into and out of said cylinders for said pistons, and means coordinating the operation of said valve means with the movement of said ring gear, said valve means comprising a valve housing associated with each of said pistons and cylinders, each of said valve housings having fluid passages formed therein, one of said passages communicating with the interior of said cylinder while another of said passages communicates with a source of high pressure and still another of said passages communicates with a source of low pressure, and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element including portions thereof protruding from said valve housing, said coordinating means comprising a cam plate carried by said ring gear and having abutment means in engagement with said protruding portions of said valve element. 6. In the combination ofa drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inn'er gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring through its orbital path whereby said inner gear and thereby said shaft is rotated,

said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced aroundand drivingly engaged with said ring gear, valve means for controlling the flow of fluid into and out of said cylinders for said pistons, and means coordinating the operation of said valve means with the movement of said ring gear, said valve means comprising a valve housing associated with each of said pistons and cylinders, each of said valve housings having fluid passages formed therein, one of said passages communicating with the interior of said cylinder while another of said passages communicates with a source of high pressure and still another of said passages communicates with a source of low pressure, and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element comprising a slidable spool valve hav ing portions at either end thereof extending outwardly of said housing,

said coordinating means comprising a cam plate carried by said ring gear, and recess means formed in the periphery of said plate with said valve housing being received in the recess and said extending portions of said valve being in engagement with the walls of said recess.

7. In the combination ofa hydraulic motor device comprising:

a housing,

a plurality of angularly spaced hydraulic cylinders in said housing,

piston means slidably received in each ofthe cylinders,

first and second driven members in said housing,

means operatively connecting each of said piston means to said first driven member whereby drive is imparted to said first driven member as said pistons reciprocate,

said first driven member drivingly engaging said second driven member,

a source of hydraulic fluid pressure,

valve means for selectively and sequentially interconnecting each of said cylinders with said pressure source,

means driven by said first driven member for controlling the operating ofsaid valve means,

said valve means comprising a valve housing associated with each of said pistons and cylinders,

each of said valve housing having fluid passages formed therein,

one of said passages communicating with the interior of said cylinder while another of said passages communicates with a source of high pressure and still another of said passages communicates with a source of low pressure, and

a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element including portions thereof protruding from said valve housing, said controlling means comprising a cam plate carried by said first driven member and having abutment means in engagement with said protruding portions of said valve element, 8. In the combination of a hydraulic motor device comprising:

a housing, a plurality of angularly spaced hydraulic cylinders in said housing, piston means slidably received in each of the cylinders, first and second driven members in said housing, means operatively connecting each of said piston means to said first driven member whereby drive is imparted to said first driven member as said pistons reciprocate, said first driven member drivingly engaging said second driven member, a source of hydraulic fluid pressure,

valve means for selectively and sequentially interconnecting each of said cylinders with said pressure source,

means driven by said first driven member for controlling the operating of said valve means,

said valve means comprising a valve housing associated with each of said pistons and cylinders,

each of said valve housings having fluid passages formed therein,

one of said passages communicating with the interior of said cylinder while another of said passages communicating with a source of high pressure and still another of said passages communicates with a source of low pressure and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element comprising a slidable spool valve, said controlling means comprising a cam plate carried by said first driven member,

means on the cam plate in camming engagement with said spool valve for controlling the sliding movement of said spool valve.

9. In an orbital drive system comprising in combination a stationary housing structure, a rotatable driven shaft, a driven gear, appropriate bearings and structure for supporting said shaft and gear, an orbital gear engaging the driven gear, and means for driving said orbital gear in, and constraining said orbital gear to, orbital driving engagement with said driven gear; the improvement in said last named means comprising a floating element, a first pair of substantially parallel links connecting said element to the housing, a second pair of links lying at about right angles to the said first pair of links and connecting said element to the orbital gear, hydraulic motors reacting between said housing and said orbital gear for driving said orbital gear, valve means for said motors, and valve actuating means carried by said orbital gear. 

1. In the combination of a drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, linkage means pivotally connected to said ring gear and said housing and supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, and means for driving said ring gear through its orbital path whereby said inner gear means and thereby said shaft is rotated, the improvement comprising: said linkage means comprising a parallelogram support for said ring gear. In the combination of a drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whEreby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, linkage means pivotally connected to said ring gear and said housing and supporting ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, and means for driving said ring gear through its orbital path whereby said inner gear means and thereby said shaft is rotated, the improvement comprising: said linkage means comprising a support ring and supporting links interconnecting said ring, ring gear and housing.
 3. In the combination of a drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring gear through its orbital path whereby said inner gear means and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear, the improvement comprising: said piston being received in radially outwardly opening cylinders formed in said inner gear means.
 4. In the combination of a drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring gear through its orbital path whereby said inner gear and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear, valve means for controlling the flow of fluid into and out of said cylinders for said pistons, and means coordinating the operation of said valve means with the movement of said ring gear, the improvement comprising: said valve means comprising a valve plate having fluid passages therein, said piston means including fluid passages in communication with the interior of said cylinders, said valve plate being supported for movement relative to said piston means whereby the passages in said valve plate are sequentially moved into and out of communication with the passages associated with said piston means.
 5. In the combination of a drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear mEans whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring gear through its orbital path whereby said inner gear and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear, valve means for controlling the flow of fluid into and out of said cylinders for said pistons, and means coordinating the operation of said valve means with the movement of said ring gear, said valve means comprising a valve housing associated with each of said pistons and cylinders, each of said valve housings having fluid passages formed therein, one of said passages communicating with the interior of said cylinder while another of said passages communicates with a source of high pressure and still another of said passages communicates with a source of low pressure, and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element including portions thereof protruding from said valve housing, said coordinating means comprising a cam plate carried by said ring gear and having abutment means in engagement with said protruding portions of said valve element.
 6. In the combination of a drive mechanism comprising: a housing, an output shaft rotatably supported in said housing, inner and outer gear means in said housing, said inner gear means being operatively connected to said shaft and said outer gear means comprising a ring gear received over said inner gear means, the inner diameter of said ring gear being substantially greater than the outer diameter of said inner gear means whereby said ring gear may assume a position eccentric to the longitudinal axis of the inner gear means, means supporting said ring gear for orbital movement relative to said inner gear means whereby the teeth of said ring gear progressively engage and disengage the teeth of said inner gear means, means for driving said ring through its orbital path whereby said inner gear and thereby said shaft is rotated, said means for driving said ring gear comprising a plurality of hydraulically actuated piston means including pistons and cylinders angularly spaced around and drivingly engaged with said ring gear, valve means for controlling the flow of fluid into and out of said cylinders for said pistons, and means coordinating the operation of said valve means with the movement of said ring gear, said valve means comprising a valve housing associated with each of said pistons and cylinders, each of said valve housings having fluid passages formed therein, one of said passages communicating with the interior of said cylinder while another of said passages communicates with a source of high pressure and still another of said passages communicates with a source of low pressure, and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element comprising a slidable spool valve having portions at either end thereof extending outwardly of said housing, said coordinating means comprising a cam plate carried by said ring gear, and recess means formed in the periphery of said plate with said valve housing being received in the recess and said extending portions of said valve being in engagement with the walls of said recess.
 7. In the combination of a hydraulic motor device comprising: a housing, a plurality of angularly spaced hydraulic cylinders in said housing, piston means slidably received in each of the cylinders, first and second driven members in said housing, means operatively connecting each of said piston means to said first driven member whereby drive is imparted to said first driven member as said pistons reciprocate, said first driven member drivingly engaging said second driven member, a source of hydraulic fluid pressure, valve means for selectively and sequentially interconnecting each of said cylinders with said pressure source, means driven by said first driven member for controlling the operating of said valve means, said valve means comprising a valve housing associated with each of said pistons and cylinders, each of said valve housing having fluid passages formed therein, one of said passages communicating with the interior of said cylinder while another of said passages communicates with a source of high pressure and still another of said passages communicates with a source of low pressure, and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element including portions thereof protruding from said valve housing, said controlling means comprising a cam plate carried by said first driven member and having abutment means in engagement with said protruding portions of said valve element.
 8. In the combination of a hydraulic motor device comprising: a housing, a plurality of angularly spaced hydraulic cylinders in said housing, piston means slidably received in each of the cylinders, first and second driven members in said housing, means operatively connecting each of said piston means to said first driven member whereby drive is imparted to said first driven member as said pistons reciprocate, said first driven member drivingly engaging said second driven member, a source of hydraulic fluid pressure, valve means for selectively and sequentially interconnecting each of said cylinders with said pressure source, means driven by said first driven member for controlling the operating of said valve means, said valve means comprising a valve housing associated with each of said pistons and cylinders, each of said valve housings having fluid passages formed therein, one of said passages communicating with the interior of said cylinder while another of said passages communicating with a source of high pressure and still another of said passages communicates with a source of low pressure, and a valve element in said housing operable to selectively intercommunicate the passages, the improvement comprising: said valve element comprising a slidable spool valve, said controlling means comprising a cam plate carried by said first driven member, means on the cam plate in camming engagement with said spool valve for controlling the sliding movement of said spool valve.
 9. In an orbital drive system comprising in combination a stationary housing structure, a rotatable driven shaft, a driven gear, appropriate bearings and structure for supporting said shaft and gear, an orbital gear engaging the driven gear, and means for driving said orbital gear in, and constraining said orbital gear to, orbital driving engagement with said driven gear; the improvement in said last named means comprising a floating element, a first pair of substantially parallel links connecting said element to the housing, a second pair of links lying at about right angles to the said first pair of links and connecting said element to the orbital gear, hydraulic motors reacting between said housing and said orbital gear for driving said orbital gear, valve means for said motors, and valve actuating means carried by said orbital gear. 